More than 75 million people fought in World War II - nearly all of them men. Who was going to produce the weapons and the food, and do countless other vital jobs? The answer was women. Millions stepped forward to take on work they had rarely done before, such as fighting fires, ploughing fields and cracking codes. These are the stories of four trailblazers who achieved amazing things in difficult circumstances: Anne-Marie Walters became a secret agent...